Arturo Vidal arrived in Spain on Sunday to pose for photographs for the first time since agreeing to become a Barcelona player. The Chilean had a big smile across his face as he stuck his thumbs up for the camera, but it's not a signing which has been universally celebrated.

Vidal joins Barca from Bayern Munich for around €20 million. If you look it has CV, it looks like a good deal. Some, though, disagree.

Age is one complaint. Chile international Vidal is 31 now and it does pose legitimate questions: Should Barca be making such short-term signings? Will he block the process of some of the younger players coming through at Camp Nou?

Another issue which has been raised is his injury history. It's something which has been made to be much bigger than it is. Vidal is only now returning from surgery on a knee problem. That's why Barca insisted on stringent medical tests, enlisting the advice of specialist Ramon Cugat, before committing to the deal.

However, to say Vidal is injury-prone would be stretching it. He's had niggles but during three years at Bayern he averaged 44 games a season. At Juventus, over the course of a four-year stay, that number was 43. He's never been a player who has missed large chunks of campaigns.

A checkered life off the field is also on the charge sheet. There have been high profile incidents, such as the time he crashed his Ferrari during the Copa America in Chile, and, again, it's fair to ask those questions.

Dwarfing all those issues, though, for the second summer running, is the debate about style: Why are Barca signing a midfielder who isn't an obvious fit for their system?

Coach Ernesto Valverde, who was asked the same questions after signing Paulinho last year, has given a very clear answer.

"I accept everyone's opinion," he said in a news conference on Friday. "But there was a lot of criticism [about the signing of] Paulinho last year, too, before he'd even played one minute for us. And look how that turned out.

"At a club like [Barcelona], there's room for everything, for different styles. It's true that some players mark our style more than others. But players like Vidal can enrich our style.

"I like the fact he's a warrior. He's someone that's aggressive on the pitch and his spirit will be contagious for the rest of the players. He can add energy in midfield, he can get forward, apply pressure, score goals... And we hope he can add all of that, while noting that his profile, as was the case with Paulinho is different to what we have -- which is important."

Variety, basically, is what Valverde is looking for. Paulinho's return to China in July, of which he was not in favour, meant he lost a little bit. With Vidal, he gets is back.

Besides, it's a relatively new argument to complain about a player's fit. Barca, traditionally, have relied on different shapes and sizes in midfield. To varying degrees of success, the club have signed Alex Song, Javier Mascherano, Seydou Keita, Yaya Toure, Edgar Davids and Mark van Bommel since the turn of the millennium. Even Ivan Rakitic wasn't an obvious fit when he signed following Xavi's departure.

Going even further back, the likes of Gica Popescu, Ramon Caldere and Victor Munoz were also players who could mix it up in the middle.

However, that also misses the point: Vidal is actually a very good all-rounder. He describes himself as a box-to-box midfielder but he's pretty much fulfilled every role possible across the middle of the pitch, including playing as a false nine at times for Chile.

There was a reason Pep Guardiola, the prototype Barca midfielder who then went on to play a big role in Xavi and Andres Iniesta's careers, signed him for his Bayern side in 2015. Under Guardiola, Carlo Ancelotti and Massimiliano Allegri, Vidal has always been a manager's favourite. In that sense, he's a much better fit for Valverde's side than Paulinho ever was.

Whether he will still be smiling by the end of the season remains unknown. But the logic behind his arrival does make sense -- there are many ways to win a football match and it would be stubborn not to acknowledge that -- even if some of the concerns raised have been fair.